A Cyclometalated NHC Iridium Complex Bearing a Cationic (η⁵‐Cyclopentadienyl)(η⁶‐phenyl)iron Backbone**.

Malchau, Christian; Milbert, Tom; Eger, Tobias R.; Fries, Daniela V.; Pape, Pascal J.; Oelkers, Benjamin; Sun, Yu; Becker, Sabine; Prosenc, Marc H.; Niedner‐Schatteburg, Gereon; Thiel, Werner R.

Nucleophilic substitution of [(η5‐cyclopentadienyl)(η6‐chlorobenzene)iron(II)] hexafluorophosphate with sodium imidazolate resulted in the formation of [(η5‐cyclopentadienyl)(η6‐phenyl)iron(II)]imidazole hexafluorophosphate. The corresponding dicationic imidazolium salt, which was obtained by treating this imidazole precursor with methyl iodide, underwent cyclometallation with bis[dichlorido(η5‐1,2,3,4,5‐pentamethylcyclopentadienyl]iridium(III) in the presence of triethyl amine. The resulting bimetallic iridium(III) complex is the first example of an NHC complex bearing a cationic and cyclometallated [(η5‐cyclopentadienyl)(η6‐phenyl)iron(II)] substituent. As its iron(II) precursors, the bimetallic iridium(III) complex was fully characterized by means of spectroscopy, elemental analysis and single crystal X‐ray diffraction. In addition, it was investigated in a catalytic study, wherein it showed high activity in transfer hydrogenation compared to its neutral analogue having a simple phenyl instead of a cationic [(η5‐cyclopentadienyl)(η6‐phenyl)iron(II)] unit at the NHC ligand.

IRIDIUM; IRON; TRANSFER hydrogenation; ELEMENTAL analysis; METHYL iodide; IMIDAZOLES

Chemistry - A European Journal, 2021, Vol 27, Issue 61, p15208

0947-6539

Academic Journal

10.1002/chem.202102520